Audio Science Review (ASR) Forum

Reviews, Technical Articles, Hardware Teardowns and Measurements of Audio Products

In my, I was asked how well the D10 does as a USB to S/PDIF (and Toslink) converter since it has those outputs. I thought I make this review and measurement its own topic.

The Topping D10 is nice and tiny and no bigger than many USB to S/PDIF converters. What's more, it has a nice display which many lack, showing the sample rate:


At $75 including shipping (albeit on Massdrop), it is also price competitive with other such converters.

Let's get into measurements and see how it does.....
This is comparison review and measurements of RME ADI-2 Pro against the RME ADI-2 DAC. The former has both analog to digital conversion in addition to digital to analog. I purchased that combo unit because I hope to make use of its ADC for measurements in the future. According to RME, ADI-2 DAC has some additional refinements in design which they say are not measurable. Well, I hope to measure them. :)

I purchased the RME ADI-2 Pro by contacting RME in Germany/US and received kind accommodation pricing. With the retail price of USD $1,999, even with my discount, it is still pretty serious amount of dollars. The RME ADI-2 DAC which I reviewed earlier, comes at a much more reasonable price of $999.

Physically the units are almost identical as far as size and general design:


The rear of the unit is much improved though. Due to lack of space, connections such as S/PDIF on RME ADI-2 Pro are relegated to a dongle which sports rather pedestrian cable and connectors...
This is a brief review and measurements of miniDSP 2x4 HD Processor and USB DAC. I purchased this online and seems like the price as of this writing is USD $207 as of this writing. This is a USB DAC with Toslink optical input and analog/digital in, four channel digital signal processor (DSP).

The DSP features can be used to implement everything from active speaker crossovers to full room correction/equalization. While the former functionality is easy enough to implement, the latter is up to you to program. This is a "raw" platform with no intelligence of its own. If you want room equalization, you have to figure out how to program its individual parametric filters or FIR parameters.

The unit comes in a shiny aluminum case that feels decent and has just enough weight to not get dragged too badly by the myriad of connections you would have to hang from it:


Above, I have the USB cable on the right....
This is a review and measurement of the Schiit Fulla DAC and headphone amplifier. It is the version 1 and is on kind loan from a member. If you are interested in V2/current version, I have purchased that, and the review will be forthcoming.

The Version 1 is a diminutive unit, a bit larger than the typical "thumb drive" sized USB DACs. It is made from folded metal like the larger Schiit products.

There are some sharp corners especially around the volume control knob that I wished were rolled off. Speaking of the volume control, it has rather low level of travel but it works and is convenient to have.

Format wise, this is an older DAC so limited to 96 kHz sampling rate as reported by Roon:

Schiit Fulla V1 DAC Roon Format Support.PNG

Yes, the USB identifier indeed says "I'm Fulla Schiit." Would be quite funny if the performance is great. Let's see if that is so in our measurements. If you are not familiar with my tests, I suggest reading my...
This is a digest of the Audio Engineering Society (AES) conference paper titled, “Distortions in Audio Op-Amps and Their Effect on Listener Perception of Character and Quality.” ( As the name indicates, it is a controlled listening tests to see if there is audible difference between Op-amps (integrated small amplifiers) when operated below their clipping point.

In recent years, it has become quite fashionable to talk about what Op-amp are used in audio products or swap one for the other in the same. While subjective outcomes abound on efficacy of such differences, question becomes if there is any formal, controlled listening tests that can give us reliable indication of audible differences in Op-amps.

The paper in question aims to answer this question. It has good pedigree when it comes to its authors which includes the famous mastering engineer, George Massenburg, and other researchers from various departments...
This is a review and measurement of Intona USB Isolator. In the last few years there has been a proliferation of USB filters, cleaners, regenerators, feeding on fear of audiophiles of noisy computer ports. Intona doesn't actually play in that market directly. They built this device for industrial control applications where strict isolation from the machine being controlled is required. Audiophiles however, have been interested in the unit just as they are in other devices in this category.

This unit is on a kind loan from a forum member. It retails for USD $229 plus $29 shipping to US. It comes in a nondescript, plastic box. No pretense of being a audio jewelry here. For this review I compared the Intona to Uptone Regen and TotalDAC D1. You can see the full collection here:


Interestingly the Intona works without any external power even though it is an active device. The Uptone Regen which is also active needs an external power supply which itself can be a source of noise (I used the iFi iPower supply that was recommended for it). I think the TotalDAC is passive but I am not sure. Either way, it doesn't need a power supply.

This is a review and detailed measurements of RME's new ADI-2 DAC. This is a spin off from their highly regarded ADC/DAC combo, the ADI-2 Pro. I have purchased the Pro for my testing but a member was kind enough to loan me the DAC only version reviewed here. I will measure and post any differences between the two at a later time.

The ADI-2 DAC retails for USD $999. The black version I received looks quite attractive with nice white LED highlights around controls and a high-resolution and highly responsive LCD display.


From a pure DAC functionality, it is better executed than my ADC/DAC. It has a remote control and unlike mine, has proper inputs for S/PDIF as opposed to a dongle.

The unit has huge number of settings and display material that is navigated through four switches and three rotary encoder, all of which are "clickable." Unfortunately this also brings with it lots of complexity and non-standard operation. For example, the click mode of right two encoders are used to scroll up and down in a menu. What??? Why not rotate the knob to go up or down and click to select?

Simple things are not simple. For example, there should be a button dedicated for changing inputs with just a click. But what is labeled as I/O just gets you into menus where you have to navigate and try to change the input without changing something else.

Fortunately there is an "auto" mode for selecting the input and if that priority matches yours, then you are good to go.

This is a review and (highly) detailed measurements of the Auralic Gemini 2000 DAC and headphone amplifier. It is on kind loan from a member who has been patiently waiting for its review! :) The Gemini is a lifestyle audio device, licensing the Klutz Design CanCan and embedding a DAC and headphone amplifier in its base:


The retail price is US $1,200. Seeing how Klutz charges $550 for its base alone, this is not an outrageous sum for a unit that adds the DAC and headphone functionality and with it, remove a lot of clutter from your desk.

Looking at the slick website and the picture of the PCB, I was salivating over its design:

Auralic Gemini 2000 DAC and Heaphone Amplifier PCB.png.jpg

This is a great use of white solder mask/silk screening of the PCB. You could literally eat off of the thing! :)

This is a "naked" review and measurements of the LH Labs Go2Pro DAC and headphone amplifier. I say naked because in in the interest of time, I am posting its results by itself. I am hoping by now you all are familiar with the norms in my measurements and can see its fidelity. Actually there is one measurement that includes a comparison.

I can't find its retail price but it is on sale now with 20% off at $480 on LH Labs website. So quite pricey. The unit is on kind loan from a member.

Anyway, this is a self-powered device (although I tested it while connected via USB) and includes a 3,200 mah battery. That combined with a metal enclosure makes for one hefty device.


I find the user interface maddening. There is a simple on/off switch but then the "up" volume control is overloaded as meaning both extra gain, and filter??? I confess I could not figure it out. :) Pushing the up volume to max did light up one of the many colored LEDs which I assumed meant high-gain. The lights are surface mount LEDs and as tiny as they can get. Seemingly they are wasted for DSD rates??? I told you that I found the interface maddening. :) Someone with more patience than me may be able to figure it out.

This is a review and detailed measurements and comparison of Massdrop Grace Design SDAC DAC. It is on kind loan from a forum member. The "drop" is over but when it was active, the unit costs $79. See it, and the detailed specs here:

The unit is similar size to JDS Labs OL DAC ($99 plus shipping) which I compared it to in this review:


Clearly they are after the same market and audience. While both have decent heft for what they are, they are both too light so support heavy cables and such.

The JDS OL DAC comes with an external linear power supply while the Grace SDAC is USB powered. The designer, Michael Grace, has written a nice post about the SDAC here: Reading that, seems like good engineering has gone into the device beyond just slapping a reference design in a box. Measurements of course will tell if that is, or is not the case.